Nuclear medicine is a unique medical specialty wherein radiation is used to acquire images which show the function and anatomy of organs, bones or tissues of the body. Radiopharmaceuticals are introduced into the body, either by injection or ingestion, and are attracted to specific organs, bones or tissues of interest. Such radiopharmaceuticals produce gamma photon emissions which emanate from the body and are captured by scintillation crystals with which the photons interact to produce flashes of light or events. Events are detected by one or more collimated gamma photon detectors, such as photomultiplier tubes. The detectors are typically rotated about a patient's body to obtain projection data from a number of different view angles. Using the gamma event data that is collected, three-dimensional images of the organs of the body, which have been taken up the radiopharmaceuticals, e.g. the heart, can be reconstructed.
In the case of SPECT, iterative reconstruction of projection images typically attempts to approximate the system matrix as closely as possible in order to improve the image quality and noise characteristics of the reconstructed images. However, modeling the system matrix can be computationally prohibitive both in terms of the amount of memory required and/or the time that is required. Consequently, attempts have been made to reduce the effort required to model the system matrix, and have included the use of optimized libraries, graphics processing units (GPU), etc. However, the above-described efforts are generally unsatisfactory.
What is needed then is a method for improving iterative reconstruction techniques so as to increase computational efficiency and reduce the time required to perform such techniques.